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Publication numberUS3252312 A
Publication typeGrant
Publication dateMay 24, 1966
Filing dateApr 25, 1962
Priority dateApr 25, 1962
Publication numberUS 3252312 A, US 3252312A, US-A-3252312, US3252312 A, US3252312A
InventorsCurtis E Maier
Original AssigneeContinental Can Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for explosive reshaping of hollow ductile objects
US 3252312 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

c. E. MAIER 3,252,312 METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OF HOLLOW DUCTILE OBJECTS May 24, 1966 4 Sheets-Sheet 1 Filed April 25, 1962 Ex H A 0 ST INVENTOR ATTORNEYS a I m .3 1. a, 5 r2 g 5 a 7 6 7 k 8 A m I 4 7 i U x G 7 2 Y\\\\\ C 4 2 E V an 2 2 5 m 3 A.

1 s 4 e z r J L L m 6 T h May 24, 1966 c. E. MAIER 3,252,312

METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OF HOLLOW DUCTILE OBJECTS Filed April 25, 1962 r 4 Sheets-Sheet '2.

Ill,

INVENTOR Curzns E. MAIEE.

&

ATTORNEYS May 24, 1966 c. E. MAIER 3,252,312

METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OF HOLLOW DUCTILE OBJECTS Filed April 25, 1962 4 Sheets-Sheet 4 7 5 I 4 F 5 I 1 A INVENTOR Cuz-ns E. MAnzz ATTORNEYS York Filed Apr. 25, 1962, Ser. No. 190,029

20 Claims. (Cl. 7256)' This invention relates in general to new and useful improvements in the manufacture of hollow ductile objects, and more particularly to a novel method of reshaping hollow ductile objects and the apparatus for accomplishing such reshaping.

Hollow objects are readily produced in quantity when the shapes of such objects are regular. This is particularly true when the objects are of constant cross section or tapered. However, when the cross section of an object is varied or the surface of the object is specially configurated, such as by embossing, the forming operation becomes very expensive and heretofore has not been feasible for production in large quantities. In accordance with this invention it is proposed to form specially shaped hollow objects by first forming regular shaped articles of ductile materials by relatively inexpensive conventional forming operations, and thereafter reshaping the regular shaped articles by an explosive forming operation which also maybe carried out at a relatively low cost,

This invention has a primary application with respect to objects formed of ductile metals, particularly those made from steel, both coated and uncoated including metal coated steel, such as tin-coated steel, aluminum, etc. However, the invention is not restricted to the shaping of ductile metal objects in that the principles of the invention may equally as Well be applied to intricately-shaped plastic objects wherein the plastic material is of the ductile type. Although polyethylene has proven to be most desirable plastic at the present, other types of plastics could be utilized, including polyvinyl chloride, polypropylene, polycarbonates, etc.

In accordance with the invention, the hollow articles which may be reshaped generally fall into three categories as follows: (1) hollow articles open at opposite ends; (2) hollow articles each having one end only thereof closed either by an integral end member or a separate end member attached by any means including welding and crimping; and (3) hollow articles having end members at opposite ends thereof with one of the end members being either integral or attached by any means including welding and crimping and the other end member being attached by any means including welding and crimping, but with one of the end members having a large enough hole to permit filling the object with an explosive gas mixture and the insertion of detonating means. When an article is provided with one or more end members at the time of the reshaping thereof through explosive forming, it is also possible to reshape the end member.

The invention is readily adaptable to numerous types of objects or articles, but finds particular advantages in the field of containers which are mass produced in regu-- ject of this invention to provide containers of all commonly used sizes, including commercially used drums, for example 55 gallon drums, wherein the containers have United States Patent been reshaped from existing and newly deviced regular shapes to be of the desired configuration.

Metal cans up to one gallon in capacity are at the present time produced at a minimum cost on existing high speed fully automatic can making equipment at the rate of 200 to over 1000 cans per minute. However, to so produce these metal cans, the shape of the side walls of the' can bodies is relatively straight-sided, simple, cylindrical, square or oblong, although it is possible for the can bodies to be tapered, and in a separate unit operation, the top and bottom ends must be manufactured and attached to the previously made can bodies, one end before, and the other end after the product for which the can was manufactured is filled into the can. Cans produced by such a method have the side wells joined at a side seam, which for the majority of products that are to be contained, must be secured either by welding, by soldering, or by applying organic sealing cements tailored to the particular product, the strength of which side seam joints decrease rapidly in the order mentioned.

Metal cans are also produced with integral bottoms, and without a side seam joint, by a single or multiple drawing or by extrusion methods, but at slower speeds, the speed being approximately 100 cans per minute. These cans are also formed at a greater cost than the customary three-piece round, square or rectangular cans made by the high speed, fully, automatic method.

On the other hand, glass and conventionally molded plastic containers, while produced at much lower speeds than the three-piece metal cans made on the high speed, fully automatic equipment, may have practically any shape that the customer desires,

Although a majority of products will continue to be packaged in the customary three-piece straight line containers, there is an increasing demand by the packaging industry for ornamental containers which cannot be filled by the present container manufacturing equipment and which require that the packaging industry draw upon glass and conventionally molded plastic containers where the cheaper ductile containers could otherwise be used. It is therefore the primary object of this invention to provide an inexpensive method of reshaping or reforming the ductile containers wherein not only the cross section of a container may be varied from the customary cylindrical cross-section, but also the surface of the container may be irregularly shaped to the desired ornamental pattern so as to meet the requirements of the packaging industry.

Another object of this invention is to provide a novel method of reshaping ductile containers which is readily adaptable to a production line, the method of reshaping the containers including the clamping of a container within a mold with the ends thereof sealed, after which an explosive mixture of gases is exploded within the sealed container and the resultant gas pressure shock wave will effect the outward expansion of the container in accordance with the configuration of the mold in which the container is disposed.

Another object of this invention is to provide a novel method of reshaping containers to desired ornamental configurations including irregular cross-sections, the method of reshaping the containers being of a nature wherein the containers may be continuously delivered by conveyor means and the reshaping takes place at a station along a conveyor so that the method is readily adaptable to existing production lines.

Still another object of this invention is to provide a novel method of quickly reshaping a cylindrical or other straight line container to desired ornamental configuration with a minimum of cost by the clamping of the container within a configurated mold and introducing into the container an inexpensive combustible gas mixture which, when ignited, will explode and the pressure shock wave resulting therefrom will produce the necessary force to effect the drawing of the container to the desired configuration which is determined by the shape of the mold.

A further object of this invention is to provide a novel method of reshaping can bodies which is readily adaptable to existing can production lines and which may be accomplished at a minimum of expense, the method being suitable for conveyor line operation and operating to remove a can body from a conveyor line of the indexing type and during the stationary portion of the cycle of operation of the conveyor, the can body may be submitted to a device which will effect the explosion of combustible gases within the can body and effect the outward flowing of the can body due to the force of a pressure shock wave resulting from the explosion so that the can body will as sume a configuration corresponding to that of the mold in which it is seated.

Still another object of this invention is to provide a novel method of reshaping can bodies, which method is suitable to can bodies which have been formed with high strength side seams of the solder type, with welded side seams and those of the seamless type, the method also being adaptable to either can bodies without ends or can bodies with one end attached thereto.

Another object of this invention is to provide a novel can body which has been reshaped to have an ornamental surface configuration and wherein the reshaping has been accomplished within a mold by the explosion of combustible gases sealed within the can body.

Still another object of this invention is to provide a novel method of reshaping cylindrical and like straight sided can bodies to have desired ornamental cross-sections and surface configurations, the method utilizing the pressure shock wave resulting from explosion of gases and being suitable for use in conjunction with both plain can bodies and can bodies having one end attached thereto.

A still further object of this invention is to provide a novel apparatus for effecting the reshaping of can bodies utilizing the pressure shock force resulting from the explosion of combustible gases, the apparatus being of the type wherein a can body may be removed from a line of 'conveyed cans during the stationary period between indexirig of the line, the apparatus then taking the removed can body and sealing the ends thereof within a split mold receiving the can body, and the apparatus further effecting the shaping of the can body within the split mold when an explosive gas mixture is ignited within the can body.

Yet another object of this inventionis to provide a novel method of forming a shaped and decorated container or like object having a lithographed surface, the method including the steps of forming a basic container shape which is lithographed in accordance with the predeter-mined intended final shape either prior to or subsequent to the forming thereof, and explosively reforming the basic container shape and with the accompanied stretching of the lithographing without damage thereto.

With the above, and other objects in view that will herein after appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the drawings:

FIGURE 1 is a schematic view with parts broken away and shown in section, showing the general details of the apparatus for removing a can body from a conveyed line of can bodies and effecting the reshaping of the can body.

FIGURE 2 is a fragmentary elevational view showing a portion of the apparatus of FIGURE 1, with the can body being initially engaged by a centering support therefor.

FIGURE 3 is a fragmentary schematic elevational View showing a portion of the apparatus of FIGURE 1 with the can body entering into the mold of the apparatus.

FIGURE 4 is a fragmentary vertical sectional view showing the can body fully seated and locked within the mold and air within the can body being withdrawn therefrom.

FIGURE 5 is a schematic view showing the introduction of a combustible gas into the can body.

FIGURE 6 is a view similar to FIGURE 5 and shows the introduction of oxygen into the can body.

FIGURE 7 is a schematic view showing the igniting of the combustible gas and oxygen mixture.

FIGURE 8 is a schematic elevational view similar to FIGURE 1 and shows the mold in its open position and the can body being lowered out of the mold.

FIGURE 9 is a fragmentary vertical sectional view showing a modified form of support for supporting and centering can bodies having ends on the lower ends thereof.

FIGURE 10 is a chart showing the maximum theoretical explosive pressure of various fuels with oxygen and air at different charging pressures.

FIGURE 11 is a chart showing the theoretical maximum explosive pressure for methane and various oxygen and air to fuel ratios.

FIGURE 12 is a chart showing the maximum rate of pressure rise of different fuels combined with oxygen for different pressure charging.

FIGURE 13 is a chart showing the maximum rate of pressure rise of different fuels mixed with air for different charging pressures.

FIGURE 14 a is perspective view of a container body formed in accordance with the invention starting with a cylindrical body.

FIGURE 15 is a fragmentary vertical sectional view taken along the line 15-15 of FIGURE 14 and shows the specific shape of the container body of FIGURE 14 and the embossing thereof.

FIGURE 16 is a perspective view of a container formed in accordance with the invention starting with a rectangular cross sectional body.

FIGURE 17 is a fragmentary vertical sectional view taken along the line 17-17 of FIGURE 16 and shows the specific shape of the container of FIGURE 16 and the embossing thereof.

FIGURE 18 is a fragmentary vertical sectional view similar to FIGURE 17 and through only an upper part of a slightly modified container wherein the embossing has been replaced by debossing.

Referring now to the drawings in detail, it will be seen that there is illustrated in FIGURES 1 through 8 a schematic showing of a step-by-step operation of reshaping a container in accordance with this invention. Although hereinafter reference will be made to the reshaping of a can, it is to be understood that various types of containers may be shaped and the invention is in no way restricted to cans. Referring first to FIGURE 1, it will be seen that there is illustrated a support 15 along which can bodies 16 are moved with the can bodies 16 being disposed in spaced relation. It is preferred that the can bodies 16 be delivered along the support 15 in a step-bystep manner in order to provide the necessary time for the reshaping operation, although if desired, the can bodies 16 could be continuously supplied and means could be provided for presenting a single can body to the reshaping mechanism upon demand.

In according with the invention, the support 15 is provided with a mounting block 17 in which there is seated a support member 18 adapted to be vertically lifted out of the mounting block 17. In addition to being seated within the mounting block 17, the support member 18 is carried by a vertically reciprocating plunger 19 for movement therewith. The plunger 19 has an upper end closure 26 and is provided adjacent the upper end thereof with an outwardly directed flange 21. -The sup port member 18 is provided with an internal recess 22 in which the flange 21 is received. The recess 22 has a greater vertical extent than the flange 21 so that upon initial upward movement of the plunger 18, there will be no movement of the support member 18 so that the upper end of the plunger 19 may enter into a can body 16 to assure the supporting and alignment of the can body 16 with the support member 18. After a slight initialupward movement of the plunger 19, the flange 21 engages the portion of the support member 18 defining the upper end of the recess 22 and the support member 18 is moved upwardly together with the plunger 19. At this time, it is pointed out that the plunger 19 may be moved upwardly in any desired manner, including the plunger 19 being part of a fluid motor.

Another support 23, which has been schematically illustrated, overlies the support and carries a clamp plate 24 which is disposed in alignment with the support member 18. The clamp plate 24 has a depending central portion 25 which serves to guide the upper end of a can body 16 to assure the proper alignment of the can body 16 with the clamp plate 24. The underside of the clamp plate 24 surrounding the depending central portion 25 is provided with a suitable sealing ring 26 which is engageable with the upper end of the can body 16 to effect the sealed closing of the can body 16. The.support member 18 will have a similar sealing ring 27 on the upper surface thereof for engaging and sealing the lower end of the can body 16.

The clamp plate 24 is provided with a suitable igniter 28 which may be in the form of a spark plug or any other suitable type of igniter. The igniter 28 is provided with suitable spaced posts 29 which are preferably positioned so as to be disposed centrally of the can body 16 when the can body 16 is engaged with the clamp plate 24.

The clamp plate 24 is also provided with a pipe 30 which extends through the clamp plate 24 and is suitably threaded therein, as at 31. The pipe 30 will be used for the purpose of exhausting a can body and supplying the necessary materials of combustion thereto inthe performance of a reshaping operation.

The support 23 has a pair of depending brackets 32 of which only one is shown. Each depending bracket 32 carries a fluid motor. 33 of the double acting type with each fluid motor 33 including an extensible plunger 34 which, in turn, supports a mold half 35. The two mold halves 35 are preferably identical, and the mold halves 35 are provided with internal configurations 36 corresponding to the desired final shape of a can body.

The pipe 30 leads to a rotating valve assembly, generally referred to by the numeral 37. The valve assembly 37 includes a housing 38 and a rotating valve member 39. The valve member 39 is only schematically illustrated, but it is to be understood to have a fixed port 40 which is continuously aligned with the pipe 30. The valve member 39 also has a rotating port 41 which is in continuous communication with the port 40.

In addition to the pipe 30 secured to the valve housing 38, there is a pipe 42 which is secured to a suitable vacuum source and will be considered a vacuum line. A pipe 43 is connected to the housing 38 for supplying a combustible gas under pressure to the valve 37. A pipe 44 is secured to the housing for delivering to the valve 37 an oxidizing agent, such as air or oxygen under pressure. A further pipe 45 is connected to the atmosphere. It is to be noted that the pipes 30, 42, 43, 44 and 45 are equally spaced about the circumference of the valve housing 38 with the exception that there is a spacing skipped between the pipes 44 and 45, there being no pipe in diametrically opposite relation with respect to the pipe 42. In accordance with the invention, it is intended that a suitable spark control device be associated with the valve 37 and when the valve 37 is positioned at the station intermediate the pipes 44 and 45, the spark device will serve to energize the igniter 28 for a purpose to be described hereinafter. Although the valve 37 may be continuously rotated, it is preferred that the rotation of the valve 37 be on a step-by-step basis in order to provide sufiicient time for the flow of gases through the various pipes.

Referring now to FIGURE 2 in particular, it will be seen that after a can body 16 has been aligned generally with the support member 18, the initial upward movement of the plunger 19 will result in the upper end of the plunger 19 entering into the lower end of the associated can body 16 and the centering of the can body 16 with respect to the support member 18.

Referring now to FIGURE 3, it will be seen that as the plunger 19 continues its upward movement, the flange 21 will serve tolift the support member 18 and that the support member 18 will engage the lower end of the can body 16. The can body 16 is illustratedin FIGURE 3 as being moved between the spaced apart mold halves 35. At this time, the valve 37 is in its EXHAUST position.

The continued upward movement of the plunger 19 results in the upper end of the can body 16 engaging the sealing ring 26 of the clamp plate 24. In the event there should be any slight misalignment of the can body 16 with respect to the clamp plate 24, the downwardly projecting portion 25 of the clamp plate 24 will automatically realign the can body 16. After the can body 16 has been tightly clamped against the underside of the clamp plate 24 so that the upper and lower ends of the can body 16 are sealed, the mold halves 35 are moved together about the can body 16 to provide a continuous mold about the can body 16. It is to be understood that the termination of the upward movement of the plunger 19 and the closing of the mold halves 35 will be effected by automatic mechanism which may be of any conventional type, including a trip lever actuated by the plunger 19, and the details of such mechanism are not an essential feature of this invention.

After the ends of the can body 16 have been sealed and the mold halves 35 moved to their closed positions, the valve member 37 is moved to its VACUUM position wherein'a vacuum is drawn through the pipe 30 so as to remove a major portion of the air trapped within the can body' 16. After the removal of this excess air has been accomplished, the valve 37 is rotated to its COMBUS- TIBLE GAS position wherein a combustible gas under pressure is delivered to the interior of the can body 16 through the pipe 30. This is best shown in FIGURE 5.

Referring now to FIGURE 6, it will be seen that the valve 37 has the valve member 39 thereof rotated to the OXYGEN position. Although it has been indicated that oxygen will be delivered to the valve 37 through the pipe 44, it is to be understood that any type of oxidizing agent may be delivered to the valve 37 through the pipe 44 and that in many instances in lieu of using oxygen, air will be delivered to the valve 37 through the pipe 44. The compressed air, oxygen or other oxidizing agent is delivered into the interior of the sealed can body 16 to mix with the combustible gas already delivered to the interior of the can body 16.

Reference is now made to FIGURE 7, wherein the igniter 28 is illustrated in the act of igniting and exploding the combustible gas mixture disposed within the can body 16. When the combustible gas mixture explodes, there will be a rapid increase in pressure within the can body 16, and while the extremely high pressure within the can body 16 has a tendency to deform the can body 16 outwardly to conform to the shape of the mold halves 35, it has been found that the shock wave caused by the high burning rate is the primary cause of the shaping of the metal through its plastic range to a very much greater elongation than would be possible by more slowly applied forces.

Referring now to FIGURE 8, it willbe seen that the plunger 19 is in the process of moving downwardly after the reshaping of the can body 16. It is to be understood that prior to the separation of the mold halves 35, and the downward movement of the plunger 19, the valve 37 will have moved to the EXHAUST position wherein the high pressure within the can body 16 will be released. The can body 16 will continue to move down with the plunger 19 until the support member 18 is seated within. the mounting blocks 17. At this time, the can body 16 will be moved along the support 15 to the right, and will be replaced by another can body 16 to be reshaped.

While the can body 16 illustrated in FIGURES 1 through 8 is of a cylindrical configuration, it is to be understood that the can body 16 could be of a square, oval or other conventional straight side cross-section including being tapered. Also, although only one shaping of the can body 16 has been specifically illustrated methodwise, it is to be understood that the can body 16 may be reshaped to any one of numerous ornamental designs and that the shape illustrated in FIGURES 7 and 8 is for illustrationv purposes only, as is clearly apparent by reference to FIGURES 14' through 18 which will be described hereinafter.

Although in many instances the can body will be reshaped prior to the placing of an end thereon, in some instances, it may be desired to place an end, such as the end 46 of FIGURE 9, on the can body 16.

In order to handle a can body having an end, such as the end 46, disposed thereon, it is necessary that a slight mordification be made in the supporting structure for the can body. To this end, in lieu of the support member 18, a support member 47 is shown seated in the mounting block 17 in FIGURE 9. The support member 47 has an internal recess 48 in the lower portion thereof in which a flange 49 projecting externally from the plunger 50 is seated. The upper end of the plunger 50 is open and a shaft 51 is disposed therein. The shaft 51 is provided with an enlarged head 52 which overlies the upper end of the plunger 51 and is seated in a recess 53 formed in the upper part of the support member 47. The upper surface of the head 52 is disposed flush with the upper surface of the support 15 to permit the can body 16 to slide thereon during the conveying of the can body 16. The shaft 51 and the head 52 are held in the upward position by means of a pin 53 which extends through a slot 54 in the plunger 50 and rests upon a suitable stop 55 disposed externally of the plunger 50 when the plunger 50 is in its lowermost position. When the plunger 50 is moved upwardly, the head 52 stays stationary while the plunger 50 and the support member 47 move upwardly with the support member 47 passing around the lower portion of the can body 16 in the area of the seam 56 between the can end 46 and the can body 16. After a slight initial upward movement of the plunger 50 and the support member 47, the head 52 will be engaged by the plunger 50 and the support member 47 to move the head 52 and the can body 16 seated thereon upwardly. The remainder of the apparatus illustrated in FIGURE 1 through 8 will be used in conjunction with the apparatus of. FIGURE 9.

When no reshaping of the can end 46 is desired, the upper surface of the head 52 will be flat or will otherwise be configurated to conform to the shape of the can end 46. On the other hand, when it is desired to reshape the can end, the upper surface of the head 52 will be configurated as is indicated at 57, for example. In the event the can 16 has a second or upper end (not shown) the underside of the clamp plate 24 will be suitably configurated either'to match the upper end of the can or to conform to the desired configuration to which the upper end is to be reshaped.

Reference is now made to FIGURES 14 and 15 wherein there is illustrated a modified form of can body, generally referred to by the numeral 60. The can body 60 has flanges 61 and 62 at the opposite end thereof for faciliating the attachment of can ends. The can body 60 wasorigin'ally cylindrical prior to the reshaping thereof and may have either a welded seam or a conventional soldered seam. The can body 60 has a plurality of vertically spaced, smoothly convexly curved body portions 63 integrally connected together by narrow, more sharply curved, concavely curved body portions 64. In addition, at least the upper one of the body portions 63 has designs 65 embossed thereon, the designs 65 being shown as stars, but being variable as desired. The can body 60 will be provided with can ends, either by welding or crimping, one before filling and the other after filling.

In FIGURES 16 and 17, there is illustrated another example of a container which may be inexpensively formed in accordance with the invention, the container being generally referred to by the numeral 66. The container 66 is initially constantly square in cross section and has an end 67 secured to the lower end thereof while still of the square cross section. It is to be noted that the upper portion 68 of the container 66 has not been enlarged although the central portion 69 theroef has been outwardly bowed and the lower portion 70 tapers downwardly to the end 67. The upper portion 68 terminates at the upper end thereof in a flange 71 for the later attachment of a second end (not shown). Although the upper portion 68 has not been increased in cross section, the upper portion 68 has been provided with suitable decorativ embossing 72.

In FIGURE 18, there is illustrated a modification of the container 66, the container of this figure being referred to by the numeral 73 and having an upper portion 74 which corresponds to the upper portion 68. However, the upper portion 74 has decorations which include embossed portions 75 and debossed portions 76.

It is to be understood that the can bodies may be lithographed or otherwise decorated prior to the explosion reshaping thereof, it being possible to accurately determine the stretching of the various portions of the can bodies or like containers and to predecorate accordingly. It is also to be understood that while the invention has been specifically described with respect to cans, the invention The invention may also be practiced with plastic containers and like objects. At the present time the commercially accepted way of forming plastic articles is to extrude a thick walled tube of small diameter and to blow the tube in a mold. This process is a slow one and there is an undue thinning of the plastic at areas of maximum stretching. Further, if the plastic container is to be provided with metal ends, the ends of the plastic container must be trimmed after the molding thereof. In accordance with this invention, it is proposed to extrude thin wall plastic tubing and to explosively reshape the same. This can be quickly and inexpensively accomplished while holding the thinning of the plastic material to a minimum. The extruded tubing may be of any desired cross section. When the plastic container is to be provided with metal ends, the ends are applied prior to the explosive reshaping of the plastic, thereby eliminating the normal trimming of the ends of the plastic member.

The primary test conducted with respect to this matter has utilized a mixture of city gas and air. The city gas utilized was of approximately 1,000 B.t.u. per cubic foot heat content, and from an economical standpoint, in many instances, this particular gas mixture may prove the most economically feasible. On the other hand, as is clearly indicated by the graphs, a much greater effect may be obtained utilizing a mixture of acetylene and oxygen. The graphs show the results obtainable with the various hydro-carbons mixed with either oxygen or air, as well as a combustible mixture of hydrogen and either oxygen or air. A hydrogen oxygen or air mixture provides a very cleanly burning fuel and may be a desirable mixture, although the maximum available explosive pressure utilizing hydrogen is not as great as that obtainable with the hydro-carbons tested. On the other hand, as is clearly' indicated in the graphs of FIGURES 12 and 13, hydrogen produces a very high maximum rate of pressure rise and is second as compared to acetylene of the gases tested. It was found during testing that the deformation of the can body was not dependent primarily on the maximum available pressure as a result of the explosion, but upon the pressure shock wave, and this is borne out by a comparison of the graphs of FIGURES l and 12, for example. The results obtainable with hydrogen were very good, although the maximum available explosive pressure utilizing hydrogen was much lower than that available with the tested hydrocarbons.

Although some gas mixtures may produce much better results than others for complicated reshaping of can bodies, where the reshaping is relatively mild, it will, of course, be economically feasible to utilize gas mixtures which produce much less pressures and have lower rates of pressure rise in that these will not be necessary and will not require the more expensive gases.

The ability to deform and reshape a container on an economically feasible basis is a great advance in the container manufacturing art in that it now permits a manufacturer of containers to provide economically containers which have ornamental configurations comparable to the ornamental configurations of containers formed of glass and conventionally molded plastic. At the same time, the comparable cost of the ornamental containers 'with respect to conventionally molded plastic and glass containers will be much less, so that the packaging industry may now have available inexpensive decorated containers as compared to the relatively expensive glass and conventionally molded plastic containers.

Although preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention is not limited to the specific structures disclosed or to the exact method steps set forth with respect to the disclosed structures, and minor modifications may be made in the invention without departing from the invention within the scope and spirit of the appended claims.

I claim:

1. A method of reshaping tubular bodies comprising the steps of enclosing an open ended tubular body within a shaped mold and sealing the ends of the tubular body, delivering an explosive gas mixture into the interior of the sealed body, and then igniting the gas mixture and thereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold.

2. A method of reshaping tubular bodies comprising the steps of enclosing a tubular body 'within a shaped mold and sealing the ends of the tubular body, delivering an explosive gas mixture under a pressure in excess of atmospheric pressure into the interior of the sealed tubular body, and then igniting the gas mixture and thereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold.

3. A method of reshaping tubular bodies comprising the steps of enclosing a tubular body within a shaped mold and sealing the ends of the tubular body, delivering an explosive gas mixture under a pressure in excess of atmospheric pressure but insufiicient to shape the tubular body into the interior of the sealed tubular body, and then igniting the gas mixture and thereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold.

t 4. A method of reshaping tubular bodies comprising the steps of enclosing a tubular body within a shaped mold and sealing the ends of the tubular body, delivering an explosive gas mixture into the interior of the sealed tubular body, then igniting the gas mixture and thereby pro-. ducing a products of combustion pressure shock wave I the steps of enclosing a tubular body within a shaped mold and sealing the ends of the tubular body, exhausting air from within the tubular body, delivering a combustible gas into the'interior of the sealed tubular body, introducing a gas containing oxygen available for combustion into the sealed tubular body with the combustible gas to form an explosive gas mixture, igniting the explosive gas mixture and thereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold, exhausting the products of combustion from the reshaped tubular body, and then removing the reshaped tubular body from the mold.

6. A method of reshaping tubular bodies comprising the steps of enclosing a tubular body within a shaped mold and sealing the ends of the tubular body, separately delivering a combustible gas and a gas containing oxygen available for combustion into the sealed tubular body to form an explosive gas mixture, igniting the explosive gas mixture and thereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold, exhausting the products of combustion from the reshaped tubular body, and then removing the reshaped tubular body from the mold.

7. The method of claim 6 wherein the combustible gas is from the group consisting of hydrogen and hydro-carbons'.

8. The method of claim 6 wherein the combustible gas is hydrogen.

9. The method of claim 6 wherein the combustible gas is a hydro-carbon.

10. A method of forming a decoratively shaped can body comprising the steps of forming a can body in the conventional manner, sealing the ends of the can body with the can body being within a mold, and then introducing an explosive gas mixture into the can body and igniting the same to explosive reform the can body to the internal contour of the mold.

11. The method of claim 10 wherein the sealing of at least one end of the can body is accomplished by securin a can end thereto in the normal manner.

12. A method of forming a decoratively shaped can body comprising the steps of forming a can body in the conventional manner, sealing the ends of the can body with the can body being within a mold, and then introducing an explosive gas mixture into the can body and igniting the same to explosive reform the can body to the internal contour of the mold, and then attaching can ends to the reformed can body in the normal manner.

13. A method of forming a decoratively shaped container comprising the steps of extruding a hollow container having a closed end in the normal manner, and explosion reforming said container within a shaped mold to the desired decorative shape.

14. A method of forming a decoratively shaped container comprising the steps of extruding a thin walled plastic polymeric tubular member open at both ends, applying a metal end member to at least one end of the tubular member, and explosion reforming the tubular member within a shaped mold to the desired decorative shape.

, 1 lvalve for selective communication with said fluid line by said valve.

16. The apparatus of claim 15 wherein said other lines include an exhaust line, a combustible gas supply line, and an oxidizing agent supply line.

17. The apparatus of claim 15 wherein said other lines include a vacuum line, an exhaust line, a combustible gas supply line, and an oxidizing agent supply line.

18. The apparatus of claim 15 together with means for energizing said ignition device in timed relation to the operation of said valve.

19. The apparatus of claim 15 wherein said support is configurated for the simultaneous explosive reforming of an end member of a hollow object closing one end thereof.

20. A method'of reshaping tubular bodies comprising the steps of enclosing a tubular body within a shaped mold and sealing the ends of the tubular body, exhausting air from within the tubular body, separately delivering under pressure a combustible gas from the group consisting of hydrogen and hydro-carbons and an oxidizing agent into the sealed tubular body to form an explosive gas mixture, igniting the explosive gas mixture andthereby producing a products of combustion pressure shock wave which outwardly expands the tubular body to conform to the shape of the mold, exhausting the products of combustion from the reshaped tubular body, and then removing the reshaped tubular body from the mold.

12 I References Cited by the Examiner UNITED STATES PATENTS 939,702 11/1909 Jones ll344 2,272,111 2/1942 Dove 133120 2,405,714 8/1946 Ryan 83'-l77 2,892,733 6/1959 Gardner et a1.

2,935,038 5/1960 Chatten 113-44 FOREIGN PATENTS 742,458 12/ 1955 Great Britain.

' OTHER REFERENCES The Tool and Manufacturing Engineer, pages 61-68, January 1962.

Advanced High Energy Rate Forming, Book II, book copyright 1962 by ASTME, article relied on entitled Explosive Forming With Gas Mixtures, by Richard E. Lingen, copyright of article 1961, report No. SP62-02, pages 1-12. (Copy in Scientific Lib.)

The Tool and Manufacturing Engineer, pages 123 126, May 1961.

Materials in Design Engineering, pages 82-87, February 1959.

CHARLES W. LANHAM, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

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Classifications
U.S. Classification72/56
International ClassificationB21D26/08, B29C49/46
Cooperative ClassificationB29C2049/4647, B21D26/08, B29C49/46
European ClassificationB29C49/46, B21D26/08